How much for a used (90%) 17-55 f/2.8?

I'm in the market for a used Nikon 17-55 f/2.8. Looking at about 90% quality, i.e. rated about "E" on Adorama, "9" on B&H or "EX+" on KEH (yeah, I know it's no exact science and there are discrepancies among the rating systems, but have to start somewhere).

What would be a fair price for this? Seems I can't find below 999 USD (one currently at that price/rating point at both B&H and KEH; not sure which one the most conservative these days).